President Obama took to Facebook Wednesday to remember the victims of the mass shooting at Sandy Hook Elementary School in Newtown, Conn., using the tragedy to call for tougher gun laws and to lecture opponents of his gun control agenda.

“We’ve tried to change. My administration has taken action to tighten the background check system and make it more efficient, strengthen enforcement of existing laws, boost gun safety technology, and help more Americans suffering with mental illness get the help they need,” Obama wrote.